Since nearly two decades, a decline of interest in scientific studies has entailed the choice of new objectives for science teaching in many countries. To put it briefly, affective factors like motivation and the development of competencies, for instance critical analysis, have received much attention, as well as new approaches to teaching, like Inquiry Based Science Education. Although multiple learning benefits are invoked in each case, also for the future citizen, there is often, de facto, a trend toward less conceptual development and structuring, be it in teaching objectives or in students' achievements. I will briefly discuss the risks of oversimplification and teaching rituals in physics, and the need for developing a critical stance in students. I will then discuss, based on two investigations at upper secondary or university level (hot air balloon, radio carbon dating), the idea that a competence like critical analysis should not be envisaged separately from a minimum conceptual development. The final discussion will bear on implications for teaching.
A second part of this talk will be given in a session about physics education: From a subtractive to multiplicative approach, two concept-driven interactive pathways on the selective absorption of light.